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Residential builders and designers seek to improve energy efficiency, indoor air quality, and comfort with in-floor hydronic radiant heating. Typically, propane-powered in-floor radiant heating is installed in kitchens, bathrooms, and home offices when building new or during a remodel, but radiant heating is increasingly being installed in walls and ceilings as well. When combined with a propane condensing boiler, these radiant heating systems can be one of the most efficient and comfortable sources of heat for a home, as radiant heat emits comfortable, evenly distributed, consistent heat.
Propane boilers can serve double duty as both a domestic hot water and home heating system, making them versatile and a convenient way to save space. A combi-boiler is a high-efficiency gas-fired dual-purpose piece of equipment that provides an unlimited supply of hot water and hydronic space heating for a large area. The single wall-mounted unit uses less floor space than two separate systems. In addition, the system utilizes propane at an extremely high efficiency because the flue gas is condensed. And, the tankless water heater is not continually heating a reservoir of hot water, further reducing energy consumption.
Propane seamlessly replaces fuel oil, so a hybrid combi-boiler in-floor hydronic system can also be used to supplement geothermal heat pumps, which lack capacity to satisfy heating loads in extremely cold temperatures. Whether it delivers thermal energy via in-floor heating or forced air, these types of systems lower geothermal costs and provide greater comfort, efficiency, and a lower electrical rate.
Client Considerations
Radiant heating systems provide long-term energy savings, but can be more expensive with up-front costs when compared to furnace installation. Be prepared to educate your clients about the bigger sustainability and comfort picture to provide a greater understanding of long-term sustainability and energy savings versus lower installation costs and higher operating costs.
Radiant heating offers an energy efficient heat source with a very efficient delivery system that allows for zoning so heat can be delivered where it’s needed. Forced-air systems can create temperature fluctuations of 3 to 5 degrees between the floor and ceiling, while radiant in-floor heating produces uniform warmth from the floor up with no temperature differences found between the floor and ceiling.
Water also delivers heat more efficiently than air. According to the U.S. Department of Energy, a given volume of water absorbs 3,500 times more heat than the same volume of air, so a 3/4-inch-diameter flexible tube can deliver the same amount of heat as a 14-by-8-inch rigid metal duct when both systems operate under typical conditions. Certain floor tiles can also help to further retain heat.
Unlike forced-air systems that circulate dust and other allergens or produce dry indoor air, a radiant heating system minimizes the circulation of allergens, creating a healthier indoor environment. This could be very important for those suffering from allergies or respiratory issues. Propane boilers also operate quietly, providing warmth without the noise of loud fans or blowers. In addition, propane can be used to fuel water heaters, gas cooking ranges, fireplaces, snow melt systems, pool heaters, and standby generators.
An Optimized Air-to-Water Heat Pump
A new radiant home heating product is coming to market: an electric air-to-water heat pump that integrates with traditional residential propane or gas boilers. The heat pump with boiler backup ensures homes remain warm even in the coldest climates and automatically switches between the heat pump and boiler based on outdoor temperatures to maximize energy efficiency and comfort. The heat pump operates during milder temperatures to improve efficiency and reduce carbon emissions, while seamlessly switching to the boiler as the always-ready backup heating source on the coldest days. Most systems switch over around 30DF (+/- 10DF).
Elliott Willey, Director of Product Management & Climate Conscious at Weil-McLain says, “The biggest improvement over a traditional hydronic system is the overall system efficiency and resulting decarbonization. You can now achieve a step-level improvement in total system efficiency (sCOP far exceeding 1.0) for the first time.” An electric air-to-water heat pump supports decarbonization by reducing gas consumption and emissions, and as part of the dual-fuel solution, the system helps improve equipment life expectancy and energy savings in all climates. This hybrid solution is up to five times more efficient than traditional boilers, providing significant energy savings and reducing environmental impact.
In addition, the heat pump operates with an eco-friendly R32 refrigerant. Willey notes, “We have designed the product with ease-of-installation in mind. Our heat pump uses state of the art R32 refrigerant and is a ‘split system’ design that does not require freeze protection, ensuring hassle-free maintenance and long-lasting performance. Operating as dual fuel and positioning the boiler as a backup extends both the life expectancy of both appliances.”
The full hybrid system can be installed together, which will have a greater up-front cost, but will save on total labor costs for the complete installation. Or, it can be installed in phases if a boiler stops working. A heat pump-ready boiler and the indoor heat pump unit are installed immediately to restore heat, followed by adding the outdoor heat pump later during the warmer months. Alternatively, a heat-pump-ready boiler may be able to be retrofitted into this system. Willey says of the flexible installation, “We emphasize minimal ‘near-boiler’ piping changes allowing you to install the hybrid solution all-at-once, via a phased approach (boiler first, heat pump later), or a retrofit upgrade (add heat pump to existing boilers).” He does caution: “To ensure the comfort, efficiency, and durability benefits of the hybrid system, the application must be properly sized. Weil-McLain has created the ECO Calc Application Sizing Tool, an industry-first tool to guarantee the correct sizing incorporating heat load, heat pump capacity, heat emitter capacity, DHW consideration, localized weather ‘bin’ data, localized utility rates, and rebates and tax credits.”
The company is targeting the boiler installed base that is predominantly in the Northeast followed by the Midwest regions, and are prioritizing active rebate programs at the state and utility levels, incentivizing decarbonization solutions for homeowners.
Radiant Home Heating: Comfortable and Sustainable Heat
As you’ve learned, there are many benefits of radiant home heating fueled by propane:
● Energy efficient heat source
● Allows for zoning, to deliver heat where needed
● Provides uniform warmth
● Efficient heat delivery via water
● Minimizes dust and allergens
● Quiet operation
● Propane can fuel numerous appliances
